---
modificationDate: May 24, 2021
title: Expo Structured Field Values
sidebar_title: Expo Structured Field Values
description: Version 0
---

Structured Field Values for HTTP, [IETF RFC 8941](https://tools.ietf.org/html/rfc8941), is a proposal to formalize header syntax and facilitate nested data.

Since it is still a work in progress, Expo maintains a custom version that only implements the following subset of the protocol defined in [IETF RFC 8941](https://tools.ietf.org/html/rfc8941):

- All key values
- String, integer, and decimal items
- Dictionaries
